The present invention relates to the field of hydraulic equipment, and more precisely to selection and braking slides for hydraulic equipment.
Systems for controlling hydraulic circuits make use of selection and braking slides to control the feeds to the various components of the hydraulic circuit under consideration.
In known manner, selection slides comprise an element that slides in a bore having ducts connected to pipes, in order to put the feed pipes of a piece of hydraulic equipment selectively into communication with pipes leading to the pistons of a motor.
Such selection slides make it possible to select reduced cylinder capacities of the hydraulic equipment. In particular, the slides make it possible to select or bypass reduced cylinder capacities of hydraulic machines in order to change the total active cylinder capacity of the machine. Such selection is used during driving or braking, particularly for machines having radial pistons and multi-lobe cams.
On such machines, the selection slide is placed between the distributor and the feed pipes of the machine.
In known manner, the various combinations of pistons and active lobes define reduced cylinder capacities (also referred to as elementary motors) for the hydraulic machine, which are sub-portions of the hydraulic machine, which, due to their combination of pistons and active lobes, and due to their symmetry, are individually capable of turning at constant velocity when fed at a constant rate. The reduced cylinder capacities may be defined by groups of lobes, or by groups of pistons.
Selection slides are typically stopped axially by means of circlips, cylindrical shells, or snap rings. Those various axial stop means must overcome several problems, in particular taking up high stresses in a small space, and allowing a degree of freedom between the various elements of the selection slide so as to accommodate possible offcentering of various well bearings associated with the slide.
However, known solutions all present drawbacks in response to those problems. In particular, those known solutions present the drawback that the stop parts are not stressed along their axis of greatest strength. Due to the dimensional requirements linked to mounting the stop parts and the need to segment them into several parts in order to allow them to be mounted about a shaft, said stop parts present considerable functional clearance leading to bending and concentrated forces being applied via point contacts, causing parts to break.
The present invention thus aims to address those problems at least in part.